Fix hangup cause passthrough regression.

Fix hangup cause passthrough regression.

The v1.8 -r369258 change to fix the F and F(x) action logic introduced a
regression in passing the hangup cause from the called channel to the
caller channel.

(closes issue ASTERISK-20287)
Reported by: Konstantin Suvorov
Patches:
      app_dial_hangupcause.patch (license #6421) patch uploaded by Konstantin Suvorov (modified)
Tested by: rmudgett
........

Merged revisions 371860 from http://svn.asterisk.org/svn/asterisk/branches/1.8

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/10@371861 65c4cc65-6c06-0410-ace0-fbb531ad65f3